After the war, Rugolo worked for Stan Kenton, who headed one of the most musically progressive big bands of the era. He and the songwriter Joe Greene collaborated on songs that made Kenton's band one of America's most popular.[1] Rugolo provided arrangements and original compositions that drew on his knowledge of 20th-century music, sometimes blurring the boundaries between jazz and classical music.

Rugolo's arrangements for album The Four Freshmen and Five Trombones propelled the group to recognition in jazz circles. It was their best selling album of all time and they still perform music from that album.